A diversity of tactics is essential for effective herbicide-resistant weed management

Weeds arguably are the most important pest complex that impacts global agriculture despite the remarkable successes of herbicides.  The control of weeds using herbicides, and the unprecedented adoption of genetically engineered crops with herbicide tolerance has been a two-edged sword.  Agriculture and humanity have both benefited from herbicidal weed management but also have accepted concomitant risks.  Weed management tactics simplified such that only one herbicide was the primary if not sole strategy used across the landscape.  While this strategy was cheap and convenient and facilitated a major change in agricultural demographics, the benefits most important to farmers also facilitated a widespread evolution of herbicide resistance in weeds.  The evolved resistance in key weeds to herbicides and glyphosate specifically, threatens crop production.  While new technologies may help address this problem in the short term, they still represent weed management based primarily on herbicides and thus will inevitably fail unless non-herbicidal tactics are included.  Including biological, cultural and mechanical weed management tactics also has risks that must be considered; these risks include higher cost, greater expenditure of time, and a loss of convenience.  However, these tactics can be highly successful at addressing herbicide resistance if used in a fashion fundamentally different than how current weed management systems have been used.  Each field should have a diverse suite of tactics included for weed management and tactics in one field should differ from those in other fields thus insuring sufficient diversity to mitigate herbicide resistance evolution and improve crop production profitability.